High-Risk HPV
About 40% of HPV strains are high-risk type. These strains have significant morbidity and mortality. These include strains, 16, 18, 31, 33, 35, 49 and more, HPV 16 and 18 being the most common of them all. The researches directed towards the cancer and HPV association is specifically with regard to these commonest strains. HPV 16 and 18 are responsible for about 70% cases of cervical cancer. High-risk types can also complicate and give rise to other cancers, in the anal, vaginal, penile and oropharyngeal cancer. The latent period for these viruses is 5-20 years.
The cancerous disposition of these strains is explained by specific viral proteins that bind to host molecules and activate certain mutations, which result in uncontrolled proliferation of cells. The result is hordes of abnormal cells infiltrating the normal tissue structure, which can give rise to dysplasia, a precancerous stage, or eventually cancer.